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DC power dropped out

3K views 20 replies 6 participants last post by  Kidd-7 
#1 ·
This morning driving into work the cruise control just shut off. This happened twice and I noticed the second time the radio turned off and back on. The accelerator pedal poped up & the snap it made caught my attention.
The car never sputtered or shut down. It's like the power just dropped out real quick. I did a quick check before walking into work, battery is 12.4v; the connectors were tight with no corrosion. Looking for any ideas or experience. It's an aftermarket radio installed by the PO, so that's where I'm going to start checking.
 
#2 ·
My guess is the alternator and/or voltage regulator on the back of the alternator is going out (so it's running only on battery power) or there's a loose connector/corrosion at the battery (so it was running on only alternator power).
I had something similar happen with an old commuter car. When the car is no longer providing as much power as needed for all the electrical accessories, stuff starts acting weird even if the car continues to run.

-g
 
#3 ·
-g: Thanks for the insight. Battery terminals are clean and tight. I'll check out the alternator and do some voltage readings and check fuses. I pulled the radio last night and drove in w/o it. The wiring is all crimp connectors and not pretty. The cruise control would not work at all. I also noticed that the clock is dark, it did light up some for a few minutes, but went dark again.
Side note: Since I bought the car the volt gauge bounces when the blinker is on. I never really though much of it b/c the blinker indicators are on either side of the volt gauge, but maybe in fact that current draw is causing the voltage to dip.
 
#4 ·
1) This all sounds like an alternator/voltage regulator issue to me.
2) most auto shops have a testbench in which they can test your alternator but keep in mind that the load on a testbench is "simulated" so a marginal alternator could pass the testbench but still fail in real world. These items do wear out.

Depending on how frugal you are, you can rebuild an alternator fairly cheap yourself (kits are on eBay). I've done it before and would do it again if you find the issue are voltage spikes (uneven voltage when measured at the alternator output.
Regards,
-g
 
#5 ·
Check the connections at the megafuse, below the outside fusebox; that's a common spot for problems.

Checking the voltage at the fusebox and tracing back while the blinker is making the voltage vary makes it easy to troubleshoot; when the voltage stops varying, the problem is between the last two points.

If it varies more than a volt at the battery itself, even with the engine off, your battery is wasted, or barely charged. :)

Charge the battery and check again; that's a sure sign of a cell that's slowly dying.

If charging the battery fixes the variation, the alternator isn't charging enough, and needs rebuilt; I've used "Victory Lap" kits from amazon with no issues. ~$20.

You may end up replacing the battery too, if the Alt has been undercharging for a long time.
 
#7 ·
Checked the mega fuse, very slight green corrosion, but northing major.
Checked the voltage after work today. with the engine running I've only got 13.4v; Even reving the engine the voltage doesn’t climb. The battery voltage does drop about 2v when starting, so that battery is dying.
The battery is a 2 year old wally world batt. I may try swapping the battery with one of my other cars and see what happens.
 
#8 ·
The limit of voltage drop on a battery during starting is to about about 8V, depending on what your engine is built to.

A 2V drop while turning the headlights on is a battery problem, not a 2V drop while starting.

I'd buy a rebuild kit for the alternator, and check the rest of the wiring; there's a problem somewhere.

Check the ground side out; I'd bet the heavy wire to the starter is going bad.

Look at the Sticky for the "Big Three" mod.
 
#9 ·
You don't think maybe it's a cruise system problem rather than voltage supply? Perhaps it's a intermittent switch or failing cruise actuator? The reason I mention this is your only symptom is the cruise turning off, right?
 
#11 ·
Well damn, I missed that. Yeah I would also be suspicious of a big voltage drop/loss somewhere.
 
#12 ·
Had to travel, but I'm back.
It is possible it's the cruise control drawing too much current, but not enough to blow the fuse. I think it's more likely corrosion on the wires.
I replaced the alternator, had one on the shelf, it seemed to improve some. I also pulled the radio and replaced the crimp connectors with solder & heat shrink, some were really loose. I data logged it going to work, the cruise held longer than before, but did fail again. Unfortunately, looking at the data I didn't see any Vdrop.
There was mild corrosion on the ground near the battery, I need to pick up a new batt term to clean that up.
I'm still a little leary of the battery though; normally when I test one I like to see no more than a 1.5v drop when starting. I'm going to do some more testing this weekend and possible swap the battery with my other car.
 
#13 ·
Big 3 question: What are the big 3? I read through posts that I found, all referring to using larger gauge wire, but I didn't see specifically what the big 3 are. I read about running a ground from the alternator mounting to the chassis, but what other wires are we talking about here?
Thanks.
 
#14 ·
Alternator to battery; battery to block; block to body.

(The "Big 3" may actually be 4 or 5, since for instance, my old 2000 Malibu went alternator --> starter post; starter post --> battery for the positive; then block --> body; body --> body; body --> battery for the negative.)

RwP
 
#16 ·
Finally got around to the Big 3 upgrade. Definitely had corrosion on the ends of some wires.
Unfortunately, it did not fix the cruise control problem. Had to make 2 trips to work today. 1st trip there and back the Cruise held. Used it most of the ~20 min highway. 2 trip in, set and held for only a couple min, then trying it again when I pushed set the radio cut off and rebooted. I'm going to pull the radio fuse and see if it will hold. Then probably look into the aftermarket stereo as the PO did a hack job on the wiring. There was a CB in this car at one time, the current radio has a mic and satellite radio, so there is a rats nest under the dash.
Any other thoughts? could it be the cruise control module is going bad?
 
#17 ·
Looking at the fuses, I see that the cruise control & radio are on the same fuse. I was going to pull the radio fuse and see if the cruise held, guess that won't work. I had been charging my phone through the radio, so I tried not charging it. The cruise still failed. But now the radio won't come back on & the dash clock is dark. Well easy, blown fuse, NOPE. Checked a couple, but none blown and not the 10 amp that the owners manual shows. Any oddities in the wiring?

Another question, there is a 30amp fuse in its own holder mounted to the side of the inside fuse box. It looks factory, anyone know what it's for? I don't see it noted in the manual. THanks.
 
#18 ·
They keep a few spares inside the fuse box.

Are you saying the radio/cruise fuse has been replaced with a higher rated fuse? I would trace all the wiring for that circuit, may be grounding out against something.

I would also re-do all the stereo wiring. You can buy an install kit from Crutchfield - it sounds as if the PO might not have used one.

I would restore all the wiring to stock for the stereo and even plug in a stocker for a few days to see if it clears up. Then once that checks out, install the stereo the right way with a proper install kit, which will include a plug that matches the factory one. Solder all connections.

Al
 
#19 ·
The fuse is a 10amp like it should be, it's not Blown. Odd. Cruise, radio & clock are non functional. I cleaned up the wiring on the head unit before and even pulled it out to check it today still looks good. I'm concerned about the amp & xover in the trunk, not sure where the PO tapped power from as the wires go up into the rear deck. Looks like my weekend is going to be tracing wires.
Also found this thread to do some Cruise troubleshooting:
http://forums.tccoa.com/6-general-t...ol-not-working-all-wanna-cruise-holidays.html
 
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